Non-uniform temperature gradients are induced in welded structures causing rapid thermal expansion-contraction and generating residual stresses and deformations. These latter are generally measured by means of experimental techniques that have limited accuracy and high costs for large structures. To circumvent these issues, the numerical simulation is proposed in the present investigation to explicitly simulate the weld filler formation during the process, thus allowing to compute the fields of temperature during the process. The simulation is based on FEM and birth-and-death procedure and is applied to the example case of a Manual Metal Arc Welding two-passes butt-welded joint made of a low carbon steel. Numerical results are compared with...